The invention herein relates to evaluating the function of a fabric, particularly, relates to evaluating the function of fabric with phase changing material.
The use of phase change material (PCM) in textiles is an alternative form of improving the thermal insulation of the textiles to the high volume insulation, which is the standard thermal insulation applied when using non-wovens. They can reduce drastically the textile material volume for the same insulation performance. It is also a unique way of transmitting comfort by absorbing excess heat and releasing it when needed. The way PCM work is explained by the fact, when altering phase, it displays a very large latent heat, and while doing so, it retains the energy and provides thermal insulation.
However, the problem is how to evaluate their performance, since it is dynamic heat insulation, different to the traditional heat resistance. To address this problem, this invention provides a method and an apparatus for evaluating the phase changing function of fabric.
Thus, the present invention is provided for solving the aforementioned problem, which is developed and based on the equation of:
xe2x80x83xcfx84P=L/qP=L*R/(tExe2x88x92tPC);
wherein L represents the total energy for altering phase; which relates the thermal resistance of the protective of PCM (phase changing material) R and the temperature difference of the phase change tP of the PCM and the environment tE to the time of thermal protection xcfx84P. Therefore, referring to the FIG. 3, the body thermal state of a fabric with phase changing material (also heated by an environment temperature device) to be evaluated its phase changing function is recorded as the FIG. 3, and comparing to the dot line, which indicates a fabric without phase changing material, it can be seen that the thermal variate of the fabric with PCM increases much slower than that without PCM (as the dot line shown in the FIG. 3). The time that a general material fabric (without any PCM) reaches the final heat flow (qmax) is substantially equal to that the PCM reaches the qP (about xc2xd qmax), and the time that PCM reaching qP takes is called efficient protection time (xcfx84P), which is the protection level of thermal; wherein the final heat flow (qmax) will be the same for both PCM fabric and non-PCM fabric after a very long time.
This invention provides a method and an apparatus for evaluating the phase changing function of fabric. First, a fabric with phase changing material to be evaluated its phase changing function is provided and positioned between a body temperature device and an environment temperature device, and two surfaces of said fabric contact with said body temperature device and said environment temperature device respectively. Then, said fabric is heated by a controller for simulating the temperature of a human body and nature environment through two control means respectively, wherein said controller is connected with said body temperature device and said environment temperature device through two control signal cables separately for controlling temperature. Said body temperature device and said environment temperature device generate body thermal signal and environment thermal signal respectively. A record device is provided for receiving said body thermal signal and said environment thermal signal through at least a feedback signal cable. At last, said record device records and outputs the efficient protection time and the body thermal variate of said fabric for evaluating the phase changing function thereof.